Lung cancer is the leading cause of cancer-related mortality in both men and women in the US and around the world. Although lung cancer incidence and mortality rates have been slowly declining over the past decade, the five-year survival rate for lung cancer remains less than 20%, as most lung cancer patients are diagnosed with advanced disease at presentation. While developing better screening and therapeutic modalities is key to improving the treatment outcome of individual patients, newer and more active measures of cancer prevention are also critically needed, especially in high-risk individuals. To date, lung cancer prevention has largely been based on avoidance or cessation of smoking or reduction of exposure to environmental lung carcinogens. Active chemopreventive intervention remains elusive for lung cancer. Recent advances in immunotherapies for lung and other cancers have indicated that the immune system can mount effective antitumor immune responses if tumor-associated immunosuppression is blocked. It is conceivable that effective antitumor immunity may be more efficiently elicited by active immunization in the prevention setting, where tumor-derived immunosuppression is believed to play a lesser role in premalignant lesions. One of the most important steps toward developing effective cancer preventive vaccines is the selection of the antigen. Emerging preclinical evidence suggests that tumor growth can be blocked or slowed by active immunization against oncoproteins (e.g. EGFR) or proteins overexpressed in cancers (tumor associated antigens). It has previously been shown that high binding affinity of peptides across multiple HLA class II alleles predicts immunogenic human epitopes. By using the in silico scoring algorithms, You, Disis and colleagues have recently shown that a rationally designed multi-peptide vaccine directed against EGFR protein could elicit robust immune responses and reduce lung tumorigenesis in a murine model of lung cancer. Recent approaches to the development of preventive vaccines for non-viral cancers have centered on strategies to target known tumor antigens discovered in established cancers. Novel and more promising target antigens for preventive cancer vaccines may be identified from careful analyses of molecular alterations in premalignant and/or malignant tissues discovered through the TCGA and other cancer genomics projects. Some of the genes overexpressed in premalignant and malignant lesions, but not in normal tissues, may be immunogenic and capable of eliciting protective antitumor immune responses. In the current project, high priority candidate genes will be selected from the list of genes overexpressed in premalignant and malignant lesions, and will be prioritized based on differential expression patterns in premalignant and malignant lesions compared to normal tissues, functional roles in physiologic or oncogenic signaling pathways if known, confirmation of antigen expression, and in silico hotspot analysis for peptide selection. Once candidate target proteins are selected, multi-antigen multi-peptide vaccines will be formulated, and preclinically evaluated for in vivo immunogenicity and antitumor preventive efficacy in a relevant mouse model of lung cancer.